/*
 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (c) 2016, 2017 Nucleron R&D LLC <main@nucleron.ru>
 * Copyright (c) 2006 Christian Walter <wolti@sil.at>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * File: $Id: mbfunccoils.c, v 1.8 2007/02/18 23:47:16 wolti Exp $
 */
#include <mb.h>
/* ----------------------- Defines ------------------------------------------*/
#define MB_PDU_FUNC_READ_ADDR_OFF           (MB_PDU_DATA_OFF)
#define MB_PDU_FUNC_READ_COILCNT_OFF        (MB_PDU_DATA_OFF + 2)
#define MB_PDU_FUNC_READ_SIZE               (4)
#define MB_PDU_FUNC_READ_COILCNT_MAX        (0x07D0)

#define MB_PDU_FUNC_WRITE_ADDR_OFF          (MB_PDU_DATA_OFF)
#define MB_PDU_FUNC_WRITE_VALUE_OFF         (MB_PDU_DATA_OFF + 2)
#define MB_PDU_FUNC_WRITE_SIZE              (4)

#define MB_PDU_FUNC_WRITE_MUL_ADDR_OFF      (MB_PDU_DATA_OFF)
#define MB_PDU_FUNC_WRITE_MUL_COILCNT_OFF   (MB_PDU_DATA_OFF + 2)
#define MB_PDU_FUNC_WRITE_MUL_BYTECNT_OFF   (MB_PDU_DATA_OFF + 4)
#define MB_PDU_FUNC_WRITE_MUL_VALUES_OFF    (MB_PDU_DATA_OFF + 5)
#define MB_PDU_FUNC_WRITE_MUL_SIZE_MIN      (5)
#define MB_PDU_FUNC_WRITE_MUL_COILCNT_MAX   (0x07B0)

/* ----------------------- Static functions ---------------------------------*/
mb_exception_enum  mb_error_to_exception(mb_err_enum error_code);

/* ----------------------- Start implementation -----------------------------*/

#if MB_FUNC_READ_COILS_ENABLED > 0

mb_exception_enum  mb_fn_read_coils(mb_inst_struct *inst, UCHAR *frame_ptr, USHORT *len_buf)
{
    USHORT          reg_addr;
    USHORT          coil_cnt;
    UCHAR           byte_num;
    UCHAR          *frame_cur;

    mb_exception_enum    status = MB_EX_NONE;
    mb_err_enum    reg_status;

    if (*len_buf == (MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN))
    {
        reg_addr = (USHORT)(frame_ptr[MB_PDU_FUNC_READ_ADDR_OFF] << 8);
        reg_addr |= (USHORT)(frame_ptr[MB_PDU_FUNC_READ_ADDR_OFF + 1]);
        reg_addr++;

        coil_cnt = (USHORT)(frame_ptr[MB_PDU_FUNC_READ_COILCNT_OFF] << 8);
        coil_cnt |= (USHORT)(frame_ptr[MB_PDU_FUNC_READ_COILCNT_OFF + 1]);

        /* Check if the number of registers to read is valid. If not
         * return Modbus illegal data value exception.
         */
        if ((coil_cnt >= 1) &&
            (coil_cnt < MB_PDU_FUNC_READ_COILCNT_MAX))
        {
            /* Set the current PDU data pointer to the beginning. */
            frame_cur = &frame_ptr[MB_PDU_FUNC_OFF];
            *len_buf = MB_PDU_FUNC_OFF;

            /* First byte contains the function code. */
            *frame_cur++ = MB_FUNC_READ_COILS;
            *len_buf += 1;

            /* Test if the quantity of coils is a multiple of 8. If not last
             * byte is only partially field with unused coils set to zero. */
            if ((coil_cnt & 0x0007) != 0)
            {
                byte_num = (UCHAR)(coil_cnt / 8 + 1);
            }
            else
            {
                byte_num = (UCHAR)(coil_cnt / 8);
            }
            *frame_cur++ = byte_num;
            *len_buf += 1;

            reg_status = mb_reg_coils_cb(inst, frame_cur, reg_addr, coil_cnt, MB_REG_READ);

            /* If an error occured convert it into a Modbus exception. */
            if (reg_status != MB_ENOERR)
            {
                status = mb_error_to_exception(reg_status);
            }
            else
            {
                /* The response contains the function code, the starting address
                 * and the quantity of registers. We reuse the old values in the
                 * buffer because they are still valid. */
                *len_buf += byte_num;;
            }
        }
        else
        {
            status = MB_EX_ILLEGAL_DATA_VALUE;
        }
    }
    else
    {
        /* Can't be a valid read coil register request because the length
         * is incorrect. */
        status = MB_EX_ILLEGAL_DATA_VALUE;
    }
    return status;
}

#if MB_FUNC_WRITE_COIL_ENABLED > 0
mb_exception_enum  mb_fn_write_coil(mb_inst_struct *inst, UCHAR *frame_ptr, USHORT *len_buf)
{
    USHORT          reg_addr;
    UCHAR           buf[2];

    mb_exception_enum    status = MB_EX_NONE;
    mb_err_enum    reg_status;

    if (*len_buf == (MB_PDU_FUNC_WRITE_SIZE + MB_PDU_SIZE_MIN))
    {
        reg_addr = (USHORT)(frame_ptr[MB_PDU_FUNC_WRITE_ADDR_OFF] << 8);
        reg_addr |= (USHORT)(frame_ptr[MB_PDU_FUNC_WRITE_ADDR_OFF + 1]);
        reg_addr++;

        if ((frame_ptr[MB_PDU_FUNC_WRITE_VALUE_OFF + 1] == 0x00) &&
            ((frame_ptr[MB_PDU_FUNC_WRITE_VALUE_OFF] == 0xFF) ||
              (frame_ptr[MB_PDU_FUNC_WRITE_VALUE_OFF] == 0x00)))
        {
            buf[1] = 0;
            if (frame_ptr[MB_PDU_FUNC_WRITE_VALUE_OFF] == 0xFF)
            {
                buf[0] = 1;
            }
            else
            {
                buf[0] = 0;
            }
            reg_status = mb_reg_coils_cb(inst, &buf[0], reg_addr, 1, MB_REG_WRITE);

            /* If an error occured convert it into a Modbus exception. */
            if (reg_status != MB_ENOERR)
            {
                status = mb_error_to_exception(reg_status);
            }
        }
        else
        {
            status = MB_EX_ILLEGAL_DATA_VALUE;
        }
    }
    else
    {
        /* Can't be a valid write coil register request because the length
         * is incorrect. */
        status = MB_EX_ILLEGAL_DATA_VALUE;
    }
    return status;
}

#endif

#if MB_FUNC_WRITE_MULTIPLE_COILS_ENABLED > 0
mb_exception_enum  mb_fn_write_multi_coils(mb_inst_struct *inst, UCHAR *frame_ptr, USHORT *len_buf)
{
    USHORT          reg_addr;
    USHORT          coil_cnt;
    UCHAR           byte_cnt;
    UCHAR           byte_cnt_verify;

    mb_exception_enum    status = MB_EX_NONE;
    mb_err_enum    reg_status;

    if (*len_buf > (MB_PDU_FUNC_WRITE_SIZE + MB_PDU_SIZE_MIN))
    {
        reg_addr = (USHORT)(frame_ptr[MB_PDU_FUNC_WRITE_MUL_ADDR_OFF] << 8);
        reg_addr |= (USHORT)(frame_ptr[MB_PDU_FUNC_WRITE_MUL_ADDR_OFF + 1]);
        reg_addr++;

        coil_cnt = (USHORT)(frame_ptr[MB_PDU_FUNC_WRITE_MUL_COILCNT_OFF] << 8);
        coil_cnt |= (USHORT)(frame_ptr[MB_PDU_FUNC_WRITE_MUL_COILCNT_OFF + 1]);

        byte_cnt = frame_ptr[MB_PDU_FUNC_WRITE_MUL_BYTECNT_OFF];

        /* Compute the number of expected bytes in the request. */
        if ((coil_cnt & 0x0007) != 0)
        {
            byte_cnt_verify = (UCHAR)(coil_cnt / 8 + 1);
        }
        else
        {
            byte_cnt_verify = (UCHAR)(coil_cnt / 8);
        }

        if ((coil_cnt >= 1) &&
            (coil_cnt <= MB_PDU_FUNC_WRITE_MUL_COILCNT_MAX) &&
            (byte_cnt_verify == byte_cnt))
        {
            reg_status = mb_reg_coils_cb(inst, &frame_ptr[MB_PDU_FUNC_WRITE_MUL_VALUES_OFF], reg_addr, coil_cnt, MB_REG_WRITE);

            /* If an error occured convert it into a Modbus exception. */
            if (reg_status != MB_ENOERR)
            {
                status = mb_error_to_exception(reg_status);
            }
            else
            {
                /* The response contains the function code, the starting address
                 * and the quantity of registers. We reuse the old values in the
                 * buffer because they are still valid. */
                *len_buf = MB_PDU_FUNC_WRITE_MUL_BYTECNT_OFF;
            }
        }
        else
        {
            status = MB_EX_ILLEGAL_DATA_VALUE;
        }
    }
    else
    {
        /* Can't be a valid write coil register request because the length
         * is incorrect. */
        status = MB_EX_ILLEGAL_DATA_VALUE;
    }
    return status;
}
#endif
#endif
